NOUS41 KWBC 161333 AAB

PNSWSH

 

Technical Implementation Notice 13-38, Amended

National Weather Service Headquarters Washington DC

830 AM EST Wed Jan 23 2014

 

To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network

          -NOAAPORT

          Other NWS Partners, Users and Employees

 

From:     Tim McClung

          Chief, Science Plans Branch

          Office of Science and Technology

 

Subject:  Amended: Updates to the Rapid Refresh (RAP) Analysis 

          and Forecast System:  Effective February 25, 2014

 

This notice was amended to reschedule this implementation for

February 25, 2014.  Also, the cloud ceiling height will not be

added to any of the pgrb output as had been announced in the

previous version of this TIN. The RAP already generates a ceiling

height that is labeled as a cloud base height (GRIB parameter =7,

level indicator = 2) that should be used by users looking for

cloud ceiling forecasts.

 

Effective Tuesday, February 25, 2014, beginning with the 1200

Coordinated Universal Time (UTC) run, the National Centers for

Environmental Prediction (NCEP) will update the Rapid Refresh

(RAP) with Version 2.0.0.

 

The changes are designed to provide overall forecast improvement

on the synoptic scale including upper-level winds, temperature

and humidity, with specific local improvement to forecasts of 

2-meter temperatures and dew points and 10-meter winds. This

implementation specifically includes:

 

- A major upgrade to the data analysis and assimilation system

- A major upgrade to the prediction model

- New parameters added to the output grids

- Update to the station list used for BUFR output soundings.

 

Details on the various changes are provided below.

 

Analysis Upgrade:

 

The RAP uses a Gridpoint Statistical Interpolation (GSI) analysis

system which now includes options originally developed for the

Rapid Update Cycle (RUC). RUC preceded the RAP--the cloud

hydrometeor analysis, the assimilation of radar reflectivity

data, and the diabatic digital filter initialization. These

options have helped improve short-range forecasts.

 

This upgrade includes the following changes to the analysis:

 

a)  using the newest version of the GSI code from the GSI code

repository

b)  using GFS ensemble background error co-variances

c)  adjusting soil moisture and temperature based on atmospheric

low-level temperature and moisture increments

d)  adding PBL-based pseudo-innovations for surface moisture

observations

e)  assimilating lightning data

f)  improvements to snow trimming and addition of the capability

of adding snow where observational data shows snow cover that is

absent in the model background

g)  improving initialization of 3-d hydrometeor (cloud) fields

from building lower-tropospheric clouds and retaining cloud

fraction information from METAR and satellite cloud data

h)  modifying radar hydrometeor specification

i)  improving assimilation of GPS precipitable water data

 

Model Upgrade:

 

The RAP model is a configuration of the Weather Research and

Forecasting (WRF) model, using the ARW core. This upgrade

includes the following changes:

 

a)  updating the Advanced Research WRF (ARW) core to version

3.4.1 from 3.2.1

b)  changing the soil model from 6 layers to 9

c)  updating version of the Thompson microphysics

d)  switching the PBL scheme from Mellor-Yamada-Zanjic (MYJ) to

Mellor-Yamada-Nakaniski/Niino (MYNN)

e)  fixing the radiation code bug to restore attenuation due to

3-d snow mixing ratio

 

Output Product Changes:

 

The RAP currently generates CONUS output on pressure levels

(pgrb) at horizontal resolutions of 13, 20 and 40 km and output

on native levels (bgrb) at horizontal resolutions of 13 and 

20 km.  RAP output is also available on a 32-km full domain grid,

an 11-km Alaska grid, and a 16-km Puerto Rico grid.  Data are

available on each grid for all forecast hours (0-18) of each

cycle.

 

The following additional parameters are added to the pgrb files

of all resolutions:

- 0-180 hPa "best" convective available potential energy and

convective inhibition

- 0-90 hPa "mixed" convective available potential energy and

convective inhibition

- simulated radar echo top

- Haines index

- thunder potential

- 0-6 km wind shear (u and v components)

- 80-m temperature, pressure, specific humidity, and u/v wind

components

- simulated brightness temperature for GOES East and GOES West

(Channels 3 and 4 for each)

- low, middle, high, and total cloud fractions

- planetary boundary layer height, computed using the Richardson

number

 

The following changes are made to all bgrb files:

- add the number of concentration of rain particles on all 50

model levels

- generate soil temperature and moisture content to reflect the

new distribution of soil levels.  Previous output was at 0, 5,

20, 40, 160, and 300 cm.  The new levels are at 0, 1, 4, 10, 30,

60, 100, 160 and 300 cm.

 

The following changes are made in all 32-km full domain files,

all 11-km Alaska files, and all 16-km Puerto Rico files:

- add height, temperature, relative humidity, and u and v wind

components at 50 and 75 hPa

- add simulated brightness temperature for GOES East and GOES

West (Channels 3 and 4 for each)

- add low, middle, high, and total cloud fractions

- add Haines index

- compute planetary boundary layer height using the Richardson

number

 

The following changes are made in all 32-km full domain files and

all 11-km Alaska files:

- generate soil temperature and moisture content to reflect the

new distribution of soil levels.  Previous output was at 0, 5,

20, 40, 160 and 300 cm.  The new levels are at 0, 1, 4, 10, 30,

60, 100, 160 and 300 cm.

- add instantaneous incoming surface long wave radiation flux

 

The following change is made in all 32-km full domain files and

in all 16-km Puerto Rico files:

- add 0-90 hPa "mixed" convective available potential energy and

convective inhibition.

 

The BUFR output will add 28 new stations to the station time

series BUFR output and relocate four existing sites. See TIN 13-

35 for information on these additions.

 

Product Delivery Time Changes:

 

Due to running the analysis code with the GFS ensemble background

error covariances, the analysis output files will be posted up to

2 minutes later than in the current version. This delay, however,

is made up during the forecast because the products for the last

forecast hour should generally match the current delivery times.

 

No changes to data availability will occur with this upgrade. 

RAP products are currently available on NOAAPORT, the NCEP

server, the NWS ftp server and on NOMADS.

 

For more general information about the RAP, please see:

 

http://rapidrefresh.noaa.gov

 

A consistent parallel feed of data will be available on the NCEP

server by early November, via the following URLs

 

http://www.ftp.ncep.noaa.gov/data/nccf/com/rap/para

 

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/rap/para

 

NCEP urges all users to ensure their decoders can handle changes

to the content, changes to content order, and volume changes.

These elements may change with future NCEP model implementations. 

NCEP will make every attempt to alert users to these changes

before implementation.

 

For questions regarding these changes, please contact:

 

      Geoff Manikin

      NCEP/Mesoscale Modeling Branch

      College Park, Maryland

      301-683-3695

      geoffrey.manikin@noaa.gov

or

      Stan Benjamin

      NOAA Earth System Research Laboratory/GSD

      Boulder, Colorado

      303-497-6387

      stan.benjamin@noaa.gov

 

For questions regarding the dataflow aspects of these datasets,

please contact:

 

     Rebecca Cosgrove

     NCEP/NCO Dataflow Team

     College Park, Maryland

     301-683-0567

     ncep.pmb.dataflow@noaa.gov

 

NWS National Technical Implementation Notices are online at:

 

   http://www.nws.noaa.gov/os/notif.htm

 

$$